I propose to pursue a method for direct electrical recording of single ion-channel fluctuations from giant liposome membranes containing detergent-solubilized, reconstituted ion channel proteins. Detergent-extracted integral membrane channels will be inserted into small liposomes by standard cholate-dialysis methods, and these will be fused together to form giant liposomes of 10 um diameter. A patchmicropipette will be applied to such a liposome, a high-resistance seal will be formed, and a patch of reconstituted membrane will be excised from the liposome. The reconstituted channels "trapped" in the patch will then be observed electrically under voltage-clamp conditions. The method will be used to study single-channel properties of three channel proteins: the K+ channels from sarcoplasmic reticulum and transverse-tubule membranes of mammalian muscle, and the Cl- channel technique so it may be used in the reconstitution of any ion channel protein. Supporting data demonstrate feasibility and possible generality of the approach in opening the way for combined biochemical and biophysical investigations of ion channel proteins.